Birth is not something I have the means to properly animate with the tools I have. Sorry! I can at least work on changing her facial expression at least, and I can probably whip up some kind of belly shrinking sequence with the images that I have. I don't know if that's good enough but it's the best I can do for now
Maybe the actual birth could be a minigame where you have to push in time with contractions. Instead of the usual model for the girl it could be a closeup of the birth, and if you miss a push prompt you lose some progress and you see the head go back in. And once the baby has crowned it's a sort of "checkpoint" in the birth where the progress can't completely restart as you push out the body
With the software I'm using, I don't have any way to make it look like a baby is coming out of her. I don't have an image of a baby that looks like it's made from the same material, and I can't edit her to have a widened birth canal. If I draw a separate image to depict the birth and don't match the model's artstyle flawlessly, it kinda makes you think "hey wait a minute that's not really her" and that sucks. I don't have the means to do justice to the miracle of birth. Sorry!
There's always other games for birth scenes! Hazumi has it, and Liz Tower Breeding Mod has a lot of it. I recommend both